1. Field of the Invention
The invention relates to an electrical terminal, and in particular, to a terminal block with a terminal housing having at least one terminal element, for example, a tension spring terminal, located within the housing, and at least one current bar. The terminal housing includes at least one lead insertion opening for inserting an electrical lead to be connected, at least one actuating opening for inserting an actuating tool for opening the tension spring terminal, and at least one test plug opening for inserting a test plug.
2. Description of Related Art
Electrical terminals, in particular terminal blocks, have been known for decades and are used in the millions in the wiring of electrical systems and devices. The terminals are usually locked on mounting rails which are often located in large numbers in a switch-gear cabinet. Primarily, screw-type terminals or tension spring terminals are used in the terminal blocks as the terminal elements, and the operating principle in the terminal-tension spring technology is similar to that of screw-type technology. That is, while in the screw-type terminals a tension sleeve pulls the lead against the current bar by actuating the terminal screw, in the tension spring terminal this function is performed by the tension spring. In order to perform that function, the pre-tensioned tension spring is opened with an actuating tool, e.g., a screwdriver, so that the lead can be inserted into the connection space through a window in the leg of the tension spring. After removing the actuating tool, the lead is pulled by the spring force of the tension spring against the current bar. In order to be able to insert the lead or the tip of the actuating tool into the electrical terminal, the terminal housing has a lead insertion opening and an actuating opening.
Electrical terminals are generally connecting terminals so that they have at least two terminal elements which are electrically interconnected via an electrically conductive connecting bar, that is, the current bar. In addition to this basic type of terminal block, there are a host of different types of terminal blocks which are specially adapted to specific applications. Examples are two-tier and three-tier terminals, and three-lead or four-lead terminals which then have a correspondingly larger number of terminal elements. In addition, there are terminal blocks which include a basic terminal and attachment plug. That is, the basic terminal has a terminal housing with at least one terminal element inside and at least one receptacle which is electrically connected to the terminal element. The attachment plug has at least one terminal element and a plug-in contact which is electrically connected to the terminal element. In this type of terminal block, the basic terminal is generally locked on a mounting rail and the attachment plug is plugged by means of its plug-in contact onto a corresponding receptacle of the basic terminal.
In order to be able to check the correct wiring prior to starting up a system or in order to be able to detect incorrect wiring as easily as possible in case of problems, electrical terminals are known in which in the terminal housing a test plug opening for insertion of a corresponding test plug is provided. The test plug opening enables the electrically conductive components, that is the terminal element or the current bar within the housing, to make contact with the test plug, and, as an alternative, to guide and securely fix the test plug.
With the increasing miniaturization of electrical devices and electrical systems, smaller and smaller switch-gear cabinets are desired. Since ever increasing electrical devices and systems must be wired to one another, the available space for the electrical terminals in the switch-gear cabinet is reduced. Therefore, there is an increasing need for so-called xe2x80x9cmini-terminal blocksxe2x80x9d which have an extremely compact construction, i.e., have only a very small width and small length.
The primary object of the present invention is to provide for an electrical terminal which enables testing while also having a very small size.
This object is achieved, for an electrical terminal, by providing a test plug opening that is located in a laterally offset manner with respect to the center plane of the terminal block and the actuating opening. In the prior art, the lead insertion opening, the actuating opening, and the test plug opening are each arranged symmetrically to the center plane, i.e., in the middle of the electrical terminal. In the present invention, the test plug opening is located in between the lead insertion opening and the actuating opening in a laterally spaced relationship with the center plane of the terminal block and the actuating opening, which enables the electrical terminal to be made with an overall dimension which is shortened when compared to those previously known.
According to a preferred embodiment of the invention, the electrical terminal is constructed such that the actuating opening and the test plug opening pass into one another, i.e., they overlap each other. Overall, then, there are only two openings, one opening being the lead insertion opening, one part of the second opening forming the actuating opening and the other part of the second opening being used as the test plug opening. In this configuration, the dimensions of the electrical terminal is still further reduced while the second opening in the terminal housing is optimally used.
There are a host of possibilities for configuring the electrical terminal which are encompassed by the present invention, particularly with regard to varying the shape, size and arrangement of the actuating opening and the test plug opening, in order to adapt to the respective use requirements, particularly when test plugs are being used at the time.